The flagging sales suggest a deceleration from the momentum for much of 2013, when 5.09 million homes were sold, the most in seven years.

"Such a picture confirms that the U.S. housing market reached its peak at the end of 2013 and further reacceleration is unlikely near term," Annalisa Piazza of Newedge Strategy said in a research note.

Home building dipped 16% in January from December, the Commerce Department said this week. Signed contracts to buy homes plunged in December, foreshadowing the January drop-off, the Realtors said in a separate report.

The weather has kept would-be buyers from venturing to open houses, while construction crews have endured work stoppages.

But sales also declined in parts of the country where weather was less of a factor. This suggested that price pressures and tight inventories are also weighing on the real estate market.

Buying fell 7.3% in Western states, the region less affected by winter storms and where average prices are the highest. That decline was significantly larger than in the Northeast, South and Midwest.

Just 26% of sales last month were by first-time buyers. In a healthy market, that figure is closer to 40%. All cash-sales accounted for 33% of all purchases, evidence that investors continue to make up a sizable share of the sales.

Existing-home sales in a healthy market would approach 5.5 million, nearly 900,000 more than the January rate. Buying has slowed during the past six months.